The invention relates to a pressure sensor, in particular to a differential pressure sensor.
Such a pressure sensor is for example known from EP 0 083 496 B 1 or from the European Patent application 03 015 055. These differential pressure sensors are formed from a semiconductor substrate, which is thinned in an inner region into a membrane. Four measurement resistances are arranged in this inner region, which are connected into a measurement bridge, so that one may detect the pressure prevailing on both sides of the membrane as a differential pressure by way of the deformation of the membrane.
It is furthermore known from the mentioned state of the art to arrange additional compensation resistances on the semiconductor substrate which surrounds the membrane as a carrier and which does not deform under the action of the differential pressure, in order to eliminate influences caused by temperature, as well as influences of the system pressure which prevails on both sides of the membrane and which acts on the periphery of the membrane on the end-sides of the carrier.
This construction however has disadvantages. Thus, the compensation resistances on the substrate must be arranged as far as possible from the membrane, in order to exclude influences on the compensation resistances due to the differential pressure acting on the membrane. This enlarges the construction of the pressure sensor. Since the compensation resistances are not subject to any influence of the differential pressure, when they are connected to the measurement resistances on the membrane, they increase the total resistance of the circuit in a purely passive manner; by which means the measurement accuracy for measuring the differential pressure is worsened.